The present invention relates to a device for fixing a flexible element to a roller.
The invention applies in particular, but without thereby restricting the scope of the disclosure, to the field of industrial protections, to the manufacture of rolling screens or guards (for example, those used to isolate machine tools) or to protect and guard certain machine parts such as slideways. Protections of this kind have flexible elements which roll up onto rollers and which can be unrolled to prevent machine parts not only from knocking against extraneous objects or coming into contact with shavings or swarf but also from being dirtied by contact with acids or pollutants in general. Similar protection devices may also be used as movable covers, strong enough to be walked on, if necessary, placed over the installation pits of large machines or as rolling covers for tanks.
The abovementioned rollers have a tubular body which revolves about its axis so as to roll or unroll the flexible element connected with it by overcoming the force exerted by one or more helical springs located inside the roller itself.
Several methods have been used up to the present time to attach the flexible element to the tubular body. According to one of these methods, one end of the flexible element is glued to the tubular body by a layer of suitable adhesive.
Although this solution has the advantage of allowing plain tubing, freely available on the market, to be used to make the roller and of dispensing with the need for mechanical parts inside and outside the tubular body, it has numerous disadvantages, the most important of which may be ascribed to the following factors:
the unavailability of non-toxic adhesives suitable for applications such as those mentioned above; PA1 the hazards created by the solvents used; PA1 the difficulty of creating a strong adhesive bond between materials of a very different nature such as, for example, plastics and aluminium alloys or aluminium alloys and stainless steels; PA1 the poor resistance of ordinary adhesives to chemicals which may come into contact with them during use; PA1 the poor resistance of ordinary adhesives to high and low temperatures; PA1 the difficulty of procuring adhesives with specific properties for applications such as those mentioned above; PA1 the impossibility of gluing "non-stick" materials such as polytetrafluoroethylene; PA1 the difficulty of knowing exactly where a guard or protection will be installed so as to be able to choose beforehand the adhesive most suitable for the ambient conditions.
Alternatively, the flexible element may be attached to the tubular body using screws, rivets and similar means.
This solution, although it eliminates many of the drawbacks of adhesives listed above, has the disadvantage not only of increasing production costs but also of creating the need for parts inside and outside the tubular body, with sharp points or edges protruding from the inside surface of the tube that may damage the spring mechanisms inside.
In yet another method of attaching the flexible element to the tubular body, the end of the flexible element is wound round and fixed to a metal rod which fits into grooves made in the outer surface of the tube.
The main disadvantage of this solution is that it may be applied only to very thin, flexible panels which, as such, can satisfy the requirements of a very limited number of applications.
Moreover, in addition to requiring tubes that are especially shaped for each specific application, this solution has the further disadvantage that the parts inside the tubular body occupy an excessive amount of space.
The aim of the present invention is to eliminate the drawbacks of all the methods listed above with a device for fixing the flexible element to the tubular body of the roller that can satisfy the requirements of a wide range of applications, particularly as regards the possible combinations of shapes, sizes and materials of the flexible element and of the tubular body.